There are many applications, for example in assembling a variety of substantially flat parts such as sheet metal elements, panels, flanges and the like, in a typical automobile. Some locational tolerance or deliberately provided sliding movement between the fastened parts is sometimes desirable. Elements for providing such fastening should be easy and inexpensive to manufacture and assemble in the finished product.
Subsequent to manufacture and sale to the ultimate purchaser, an automobile may see service for a long time before maintenance and/or repair needs require temporary disassembly of the fastened parts. Unless it is designed appropriately, a person seeking to disassemble the fastening system will encounter problems, e.g., elements may have rusted in place, or water leakage may have caused corrosion and materials deterioration. The typical automobile often is also exposed to significant changes in temperature, humidity, and operational stresses. Therefore, unless the fastening system inherently possesses a certain controlled amount of give or tolerance, the initially correctly assembled parts will very likely be unduly stressed, possibly warped, and difficult to reassemble upon completion of whatever repairs required their disassembly.
Highly economical and efficient fastening systems are known wherein one element is easily located in or affixed to one of the substantially flat parts to be fastened. The other part to be fastened is then placed in a predetermined relationship therewith and a second element of the fastening system is employed to obtain the desired engagement. The actual act of fastening the elements of the fastening system may involve engagement of threads, deformation of expandable segments of the elements of the fastening system, and assorted combinations of twisting, turning and clipping actions.
An example of a known fastening system is taught in British Patent No. 1,588,556, to Shilson, titled "Turn Release Fastener", which employs a quick release stud releasable from a socket by rotation of the stud by a quarter turn. The socket in the system is formed to have a pair of opposed and parallel abutments resiliently biased toward one another and arranged to receive the stud, and is previously attached to one of the substantially flat parts which are to be fastened together. The stud has a partially spherical head provided with a recess for engagement by a turning tool, a straight cylindrical shaft portion and a head portion having a leading end for entering between the abutments. During use, the stud is engaged with the socket by entry of the leading end of the shank of the stud between the amendments, forcing the abutments apart until shoulders provided thereon have been passed through, the abutments thereafter resiliently closing to enter into recesses provided for retention of the stud within the socket. The socket is stamped and formed from a single piece of metal.
British Patent No. 1,519,357, to Wright, titled "Improvements Relating to Fasteners" teaches a fastening system in which a one-piece receptacle includes a pair of clip-like legs, the free ends of which extend toward one another for engagement with depressions or grooves formed in the shank of a complementary stud to retain it once it is pushed into the receptacle. The receptacle is previously attached to one of the substantially flat parts that are to be engaged together, and the stud passes through the other of such parts. The receptacle is preferably formed from spring steel. The stud has a flat domed head, including a recess to receive a tool such as a screw driver, and a shank which includes a first cylindrical part and a second larger diameter cylindrical portion having flat tapering surfaces which converge to form a waist. The end of the stud removed from the head has a generally conical tapered portion including flat chamfered surfaces. The stud is retained within the receptacle by a resilient washer.
Numerous other fastening systems are known and used but none of them provide exactly the right combination of economy, ease of installation and use and, most importantly, a predetermined degree of tolerance or freedom of relative movement for the fastened parts to accommodate the needs of workers assembling the product initially and persons seeking to temporarily unfasten the fastened parts to access other elements located behind the fastened parts or to perform repairs thereon, and finally to allow fastener components to expand and contract with changing temperature.
Accordingly, there is a definite need for a simple, inexpensive, easily installed, readily engageable and disengageable fastening system for fastening together two substantially flat parts with a built-in tolerance or freedom of relative movement therebetween in a selected direction.